Cell migration, the translocation of individual cells or whole tissue rudiments from one site in a developing embryo to another, is a critical component of morphogenesis. One very specific example of such active morphogenetic movements is seen in the development of the urogenital system. Pronephric duct cell migration in the axolotl, Ambystoma mexicanum, provides an excellent model system for studying the mechanisms controlling cell migration in vivo. Here, experiments are designed to identify, characterize and perform functional studies on specific cell surface molecules which have been implicated in the directed cell migration of A. mexicanum pronephric duct. These candidate molecules belong to two cell adhesion families, those representing cadherins and integrins. A PCR- based approach has been used to identify the expression of the candidate molecules during pronephric duct morphogenesis in the axolotl. The temporal and spatial expression of the candidates will then be assayed using Northern blotting, RNase protection assays and whole mount in situ hybridizations. Functional studies utilizing chromophore-assisted laser inactivation (CALI) will be used to inactivate each candidate molecule and determine whether its function is essential for normal pronephric duct cell migration.